1. Field of the Invention
The present invention relates to interfaces between computers and video monitors, and more particularly to an interface that multiplexes analog and digital signals for the purpose of using one set of lines between a computer system and either an analog monitor or a digital monitor.
2. Description of the Related Art
The substantial growth of the personal computer is due, in part, to the technological breakthroughs in computer design. A typical personal computer system available today includes a plethora of peripheral devices undreamed of in years past. Today a computer system available to a typical consumer might include a system processor, associated memory and control logic, and a number of peripheral devices, including a display monitor, a keyboard, a mouse-type input device, floppy and hard disk drives, CD-ROM drives, a laser printer, a color scanner, a modem, network capabilities and even a voice recognition device.
An important peripheral available in a personal computer system is the video monitor. From the time of the television set to today""s newer digital-type displays, technology has expanded the capabilities of video monitors. As a result of technological breakthroughs in video monitors, higher resolutions, faster refresh rates, and different types of video monitors are available at reasonable prices. One type of video monitor, the digital video monitor, has been improved upon and is becoming increasingly popular. A typical computer system may provide a connector for both digital and analog video monitors. What is needed is one set of lines that can connect either a digital or an analog video monitor to a computer system.
A connector with a single set of signal lines interfaces a computer system to either an analog display or a digital display. A video signal in digital format and a video signal in analog format are both supplied to a circuit that multiplexes the digital signal and the analog signals, generating appropriate output signals for the display, either analog or digital, that are coupled to the computer system.
In one example, the set of signals interfaces the computer system to either an analog cathode ray tube (CRT) display or a digital flat panel display (FPD). The multiplexer multiplexes the analog signal and the digital signal supplied by the computer system and generates an output signal that is suitable for the CRT display or the FPD display, depending on the type of display coupled to the computer system.
In one embodiment of the present invention, an apparatus includes a video controller, a connector and a circuit coupled to the video controller and coupled to the connector, the circuit selectively coupling one of either an analog video signal and a digital video signal received from the video controller to a video monitor. In another embodiment, an apparatus includes a switch, a first input terminal coupled to the switch for receiving an analog signal, a second input terminal coupled to the switch, for receiving a differential digital signal, and an output terminal coupled to the switch, the switch for multiplexing the analog signal and the differential digital signal, and the output terminal for supplying a multiplexed signal. In a further embodiment, a computer system includes a processor, a video monitor coupled to the processor, a controller, and a circuit coupled to the video controller and coupled to the connector, the circuit selectively coupling one of either an analog video signal and a digital video signal received from the video controller to a video monitor.